1. Field of the Invention
The present invention relates to a distance measurement system which projects irradiation light onto a detection object and calculates information of distance to the detection object, and relates to a distance measurement method.
2. Description of the Related Art
A known distance measurement system projects light towards a detection target area, picks up an image of reflected light returned from the detection object because of specular reflection and/or scattering by means of a pick-up device such as a CCD, and processes information of the picked up image to measure the distance to the detection object or a shape thereof. In the case where the projected light is specularly reflected, the specularly-reflected light is sometimes next scattered and incident onto the pick-up device as multiple reflected light, thus providing incorrect distance information. In other words, the presence of such multiple reflected light makes it difficult to obtain highly-accurate distance information.
Accordingly, in order to eliminate the influence of multiple reflection, a conventional distance measurement system using a space code judges the presence of multiple reflection by allocating a predetermined space code to projection angle of measurement beam projected at the irradiation step and judging whether the space code increases or not in the picked up image information (see Japanese Patent Unexamined Publication No. 2000-193438).